1. Field of the Application
The present application relates to recirculation leakages at a bladed rotor of an axial turbine engine. The present application also concerns a compressor of an axial turbine engine. The present application also proposes an axial turbine engine such as a turbojet aero engine.
2. Description of Related Art
A compressor, like a turbine of a turbojet aero engine, has a series of rows of vanes. Some of these rows are linked to the stator and others linked to the rotor. The definition of the profile of the vanes allows the processing of annular flows, by causing them to be compressed or expanded to recover energy. The efficiency of these mechanical actions on the flow depends on management of parasitic discharges.
In fact, on operation of the turbine engine, leakages pass around the rows of stator vanes. They can circulate between the rotor and the inner shroud. These recirculations cause losses by mixing. They are reflected in a reduction of the flow which is effectively compressed, and in an increase of the flow upstream of the stator vane row concerned.
The increase may have the effect of blocking or limiting the flow which can be utilised by said vane row. Re-injection of the recirculations—or parasitic leakages—degrades the flow at the feet of the stator vanes. The stability of the compressor deviates from an acceptable level. The thermodynamic behaviour is also affected, in particular due to the creation of entropy.
In order to avoid or at least limit the effects of these recirculations, it is known to provide orifices to recover the recirculations. The recirculations are then intercepted and evacuated via the orifices. They leave the primary flow which can no longer be disturbed. Operation is then preserved.
Document EP1643136A1 discloses a compressor of an axial turbine engine. The compressor has several rows of fixed vanes, the inner ends of which carry the inner shrouds. The shrouds cooperate with rubbing strips and have extraction orifices arranged between the rubbing strips. The vanes comprise inner cavities which form communication channels between the extraction orifices and an external plenum. The operating pressure of the plenum is lower than that of the extraction orifices. Therefore a parasitic discharge circulating below the inner shroud can be aspirated via the extraction orifices then evacuated via a plenum. This solution adds thickness to the vanes for housing a cavity therein. The vanes of a low-pressure compressor are generally fine, and consequently this solution is not satisfactory. In addition, this configuration generates an additional cost for housing the cavities.
Although great strides have been made in the area of compressors for axial turbine engines, many shortcomings remain.